1. Field of the Invention
The invention relates generally to devices and methods for heating subterranean hydrocarbon-bearing formations.
2. Description of the Related Art
Thermal heating is needed or desired for extraction of some hydrocarbons. In formations that have heavy oils, heat is used to stimulate flow. Heating is also useful to help release oil from shale. Steam assisted gravity drainage (“SAGD”), for example, injects steam for extraction of hydrocarbons. Radio frequency (“RF”) heating arrangements are discussed in U.S. Pat. Nos. 8,210,256 and 8,408,294 by Jack E. Bridges.